1. Technical Field
Present invention embodiments relate to reducing computational workload for query evaluation, and more specifically, to reducing computational workload by utilizing information in zone maps to govern conditional exits from table scans.
2. Discussion of the Related Art
Searching for information using a query may result in a search of a large database table. Information stored in a large database table is typically not maintained in sorted form due to heavy computational cost associated with sorting and reorganizing. Indexing, which maps a set of data values onto a set of records that relate to those data values, may be used to provide the effect of storing the data in sorted order. However, distributed data warehouses that store large database tables may split a set of records across multiple storage disks, and co-locating a portion of the index that maps a given data value with the records that relate to that data value may require additional network overhead, leading to poor latency and increased computational workload.
When query evaluation requires scanning a large table, some data warehouse management systems may maintain metadata about each region of table storage.